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Guided Bomb Unit-12 (GBU-12) Paveway II

The Guided Bomb Unit-12 (GBU-12) utilizes a Mk82 500-pound general purpose warhead. The operator illuminates a target with a laser designator and then the munition guides to a spot of laser energy reflected from the target. The GBU-12 is a member of the Paveway II series of laser guided bombs (LGBs). These weapons are hybrids. At the core of each is a bomb: a 500-pound Mk 82 for the GBU-12, a 1,000-pound Mk 83 for the GBU-16 and a 2,000-pound Mk 84 for the GBU-10. A laser guidance kit is integrated with each bomb to add the requisite degree of precision. The kit consists of a computer control group at the front end of the weapon and an airfoil group at the back. When a target is illuminated by a laser - either airborne or ground-based - the guidance fins (canards) react to signals from the control group and steer the weapon to the target. Wings on the airfoil group add the lift and aerodynamic stability necessary for in-flight maneuvering.

As the Vietnam War progressed and experience with laser guided bombs increased, Air Force leaders discovered the need for a greater variety of LGBs to increase effectiveness against certain targets. A smaller bomb with greater maneuverability was also required to attack the many small and moving targets on the Ho Chi Minh trail. The Air Force adapted the 500 lb Mk-82 GP, later called the GBU-12, for this purpose and the M-117 LGB was phased out of production in 1968.

In the early 1970s, the initial PAVEWAY was replaced by the PAVEWAY II, which featured an enhanced but also simpler and cheaper seeker head and pop-out fins to improve the weapon's glide characteristics and make it easier to fit to an aircraft. The new LGBs based on the PAVEWAY II were given the designations GBU-12 (225 kilograms), GBU-16 (450 kilograms), and GBU-10 (900 kilograms). The PAVEWAY II required the launch aircraft to operate from medium altitude, leaving the aircraft vulnerable to ground defenses.

In 1976, a GBU-12 bomb, on separating from the delivery aircraft, an F-4, was observed to pitch up as the ejectors kicked it away from the parent aircraft. The store continued to rotate nose.up until the resulting angle-ofattack was sufficiently large to generate a lift force greater than the weight and consequently the muiiition "flew" back into the F-4, impacting the wing and the externally carried fuel tank.

Over 160 missions of GBU-10 and GBU-12 bombs had been flown previously, and fin failures on approximately 5 percent of those missions had not evinced an aircraft safety problem. Since there had been no flight safety problem in the past, it was hypothesized that the failure of the fins to open had actually compounded a problem due to (1) an unprecedented adverse interference flow field, (2) out-of-tolerance mass properties, or (3) a rack malfunction.

The orifices removed from the dismantled rack were compared. It was found that even though they were stamped identically, the bore sizes weme different. The consequence of unequal orifices in the rack would be an ejector force imbalance, and there would be a resulting moment applied to the store. Validation of the premise that the ejector force mismatch had coupled with the fin failure to cause the aircraft/weapon collision was undertaken by means of computer simulations of the separation event.

The munition was used during Operation Desert Storm, and, according to the Air Force, hit 88 percent of its targets. During Desert Storm the GBU-12 was dropped by F-111Fs, F-15Es, and A-6s, mostly against fixed armor. It was the F-111F tank-busting weapon of choice. Of the 4,493 GBU-12s employed, over half were dropped by the F-111F. An aircraft using an unguided general-purpose (GP) 500-pound (lb) bomb (i.e., a Mk-82) to attack a dug-in tank has a low probability of success in comparison to a laser-guided 500 lb weapon (i.e., a GBU-12) because the accuracy of the latter is much better. Tank plinking, expending a single 500-pound GBU-12 worth $10,000 to destroy a $1.5 million T-72 tank, is not a bad return on tax dollars.

There are two generations of GBU-12 LGBs: Paveway I with fixed wings and Paveway II with folding wings. Paveway II models have the following improvements: detector optics and housing made of injection-molded plastic to reduce weight and cost; increased detector sensitivity; reduced thermal battery delay after release; increased maximum canard deflection; laser coding; folding wings for carriage, and increased detector field of view. (Paveway II's instantaneous field of view is thirty percent greater than that of the Paveway I's field of view).

The MQ-1 Predator can carry AGM-114 Hellfire missiles capable of piercing armor. The next generation MQ-9 Predator is designed to haul up to 3,000 pounds of external ordnance to include the GBU-12, GBU-38, AIM-9 missiles and small diameter bombs. The Predator's missions include ISR, close air support, interdiction, damage assessment, combat search and rescue (locating downed pilots), force protection (locating improvised explosive devices) and remote operations video enhanced receivers operations. The MQ-9 will provide a hunter-killer capability and will feature the ability to use synthetic aperture radar to hunt for targets. It will be able to cross-cue targeting data to the electro-optic/infrared sensor.

The Enhanced-GBU-12 [EGBU-12] is a dual-mode guided bomb designed to effectively operate in all-weather conditions. Enhanced Paveway II features a GPS-aided Inertial Navigation System as well as a laser guidance system to offer one precision guided weapon for all situations. The resulting dual-mode capability offers true all-weather operational flexibility not found in other weapons systems being produced: GPS guidance for poor weather conditions and precise laser guidance when required for mobile targets of opportunity. Combat proven by the RAF during Operation Southern Watch, Operation Enduring Freedom and Operation Iraqi Freedom, the Enhanced PavewayT II DMLGB combines the strengths of both laser guidance and GPS/INS guidance to create a low-cost, all-weather, precision strike weapon. The result provides the warfighter with the option for autonomous GPS-aided guidance in addition to laser terminal guidance. All-Weather

The addition of the GPS/INS system to the PavewayT II LGB weapon provides increased delivery accuracy, better in-flight wind corrections, increased low-level performance, and expanded delivery envelopes. The unique dual-mode capability of the Enhanced PavewayT II DMLGB offers considerable operational flexibility not currently available with any other weapon outside the PavewayT II family of weapons. Specifically, GPS guidance can be used for all-weather attacks of known targets; and laser guidance provides an option for improved accuracy, man-in-the-loop, moving targets, and targets of opportunity when GPS is denied. Enhanced PavewayT II DMLGB is currently fielded in the RAF inventory and has already proven itself in combat as the weapon of choice for the RAF in Operation Iraqi Freedom.

On 07 June 2006 two F-16Cs dropped two precision-guided 500-pound bombs - a GBU-12 laser-guided bomb and a GBU-38 Joint Direct Attack Munition - destroying the terrorist safe house where Al Zarqawi and other terrorists were meeting.

Specifications

Class

500 lb. Paveway I & II Guided Weapon

Mission

Air interdiction

Targets

Mobile hard, fixed soft, fixed hard

Service

Air Force, Navy

Contractor

Texas Instruments

Program status

Operational

First capability

1976

Guidance

Semi-Active Laser (man-in-the-loop)

Control

MAU-157 Series (Paveway l) MAU-169 Series (Paveway II)

Autopilot

Bang-Bang Mode

Weight (lbs.)

800

Length (in.)

129

Diameter (in.)

11 (Warhead); 18 (Airfoil Group)

Warhead

MK-82 Blast/Fragmentation

Explosive

Tritonal, PBXN-109 (192 lbs.)

Fuze

FMU-81 Tail

Range

8 nautical miles

Circular error probable

9 meters

Quantity

Air Force: 29,654 Navy: 2,982

Development cost

Air Force officials state that they could not provide development
cost because they do not have records covering the development
period.